A finisher has a function of driving staples into sheets manually inserted into an apparatus body in addition to a function of driving staples into sheets supplied from an image forming apparatus.
A user manually inserts a bundle of sheets from an opening on a discharge side of the finisher onto a processing tray. The user designates a stapling position with an operation panel and presses a manual stapling key. A controller causes a stapler to operate. The stapler is guided by a rail to move.
The processing tray leads the sheet bundle to the stapler with, among long sides and short sides of the sheets, the long sides set orthogonal to a sheet moving direction on the processing tray. Alternatively, the processing tray leads the sheet bundle to the stapler with the long sides set parallel to the sheet moving direction.
One sheet has four sheet edges in the front and the back with respect to a direction in which the sheet moves forward and in front and rear. The front and the rear respectively indicate a front side and a rear side of a main body of the finisher. The sheet edges indicate sheet margins spaced away from sheet ends.
The processing tray leads sheets manually inserted by the user to the stapler with the front edge of the sheets faced to the stapler. The stapler drives a staple into any one of three areas of the sheets explained below.
A first area is a place at a front side corner. A second area is a place at a rear side corner. A third area is two places respectively spaced at equal intervals from the center of a sheet edge.
In stapling of the two places in the center of the sheet edge, after the stapler completes the stapling in a first stapling position, the stapler moves to a second stapling position. The stapler drives a staple in the second stapling position.
A stapler moving mechanism needs stapling position information. The stapling position information indicates stapling positions of the two places in the center of the sheet edge. A controller notifies the stapler moving mechanism of position information of a first point on the rear side from the center of the sheet edge and position information of a second point on the front side from the center of the sheet edge.
However, the stapler moving mechanism cannot obtain the stapling position information of the two places in the center of the sheet edge of the sheets manually inserted by the user.
The stapler cannot staple stapling positions of a pair of two places in the center of a sheet edge of sheets, a sheet size of which is unknown.
The sheet size is standard or nonstandard. Positions at a front side sheet end and a rear side sheet end are not fixed for the stapler.
A sheet edge facing the stapler is a sheet long side or a sheet short side. The positions at the front side sheet end and the rear side sheet end are not fixed for the stapler.
A position of a front side sheet end of inserted sheets is different in each operation for inserting the sheets. On the processing tray, the user is likely to place a sheet bundle in any place in a moving direction of the stapler. The positions at the front side sheet end and the rear side sheet end are not fixed for the stapler.